In recent years, there have been extensive efforts in secondary schools to prevent, treat and raise awareness of adolescent mental health problems. For some adolescents, these efforts are essential and will lead to a reduction in clinical symptoms. However, it is also vital to assess whether, for others, the current approach might be causing iatrogenic harm. A growing body of quantitative research indicates that some aspects of school-based mental health interventions increase distress or clinical symptoms, relative to control activities, and qualitative work indicates that this may be partly due to the interventions themselves.